The Pain of Being a Redhead - Well Blog - NYTimes.com:
A growing body of research shows that people with red hair need larger doses of anesthesia and often are resistant to local pain blockers like Novocaine. As a result, redheads tend to be particularly nervous about dental procedures and are twice as likely to avoid going to the dentist as people with other hair colors, according to new research published in The Journal of the American Dental Association.
Researchers believe redheads are more sensitive to pain because of a mutation in a gene that affects hair color. In people with brown, black and blond hair, the gene, for the melanocortin-1 receptor, produces melanin. But a mutation in the MC1R gene results in the production of a substance called pheomelanin that results in red hair and fair skin.
The MC1R gene belongs to a family of receptors that include pain receptors in the brain, and as a result, a mutation in the gene appears to influence the body’s sensitivity to pain. A 2004 study showed that redheads require, on average, about 20 percent more general anesthesia than people with dark hair or blond coloring. And in 2005, researchers found that redheads are more resistant to the effects of local anesthesia, such as the numbing drugs used by dentists.
It's also nice to hear that the research came from taking this sort of common experience seriously, rather than simply dismissing it:
Dr. Daniel I. Sessler, an anesthesiologist and chairman of the department of outcomes research at the Cleveland Clinic, said he began studying hair color after hearing so many colleagues speculate about redheads requiring more anesthesia.
‘The reason we studied redheads in the beginning, it was essentially an urban legend in the anesthesia community saying redheads were difficult to anesthetize,’ Dr. Sessler said. ‘This was so intriguing we went ahead and studied it. Redheads really do require more anesthesia, and by a clinically important amount.’
If I had red hair, I would bring a copy of the paper with me to the dentist/doctor to help them take my needs seriously.*
*Just as I would, for example, show literature on the usefulness of pre-incision lidocaine in lowering post-surgicial pain to my surgeon.
I might also post articles on the problems with using morphine in patients with kidney problems on the wall by an elderly relative's hospital bed.